Stalls could occur when the approaching airflow was not in-line with the aircraft inlet to the compressor or when the throttle was advanced too quickly.

This has the advantage of being more efficient than allowing valuable compressed air to escape, although fuel consumption at low speeds is relatively unimportant.

Further increases in pressure ratio, demanded by government procurement agencies and commercial airlines for long-range aircraft, caused a bigger mismatch of flow areas/density changes and blade angles.

Two approaches were followed: slowing the blade speeds at the front of the compressor by splitting it into two separately rotating parts (spools) or making stators variable on the first few stages as well as the inlet vanes.

Bleed valves, two or three spools and variable stators are all used together on modern engines to cope with rotating stall during starts and at low speeds and to allow surge-free fast accelerations.

Parker, Speas and Neil Burgess, who ran the J79 program, spent a month meeting with American Airlines, Delta, United, KLM, Swissair and SAS.

[10] Around the same time, Convair was canvassing US carriers and found demand for a smaller jet aircraft for medium-range domestic routes.

Burgess responded by quickly sketching a version of the J79 with the afterburner removed and replaced by a thrust reverser, giving them an estimated unit price of $125,000 per engine.

There was already a lawsuit, by residents around Newark airport, concerning the noise from existing propeller-driven aircraft such as the Lockheed Super Constellation, Boeing Stratocruiser and Douglas DC-7C.

[12] One way to reduce this problem is to mix cold air into the jet exhaust, which was accomplished on early engines with the addition of scalloped nozzles.

These designs both had twin-spool compressors, as opposed to using variable stators, and the lower speed of the front, low-pressure, spool made it easy to power a fan.

[14] The problems RR and P&W had addressed with the two-spool system had been solved on the J79 with the variable stators, so in relative terms, the single compressor rotational speed was much faster than the low-pressure stage of these other engines.

Instead, GE solved this problem with the addition of a completely separate fan system at the rear of the engine, powered by a new turbine stage.

[16] Running freely on a stub shaft, a series of buckets, mounted on a disc, made up the aft rotor assembly.

In 1961, Sud Aviation approached GE to pitch them on the idea of adapting the Rolls-Royce Avon powered Caravelle to the 805-23, producing a flying technology showcase for both companies.

[22] Rolls-Royce quickly built and tested an aft-fan demonstrator Avon to compete with the greater thrust and lower specific fuel consumption of the CJ805-23.

Wright management refused to put more money into the program to improve the engine, leading to a serious backlash from the customers.